date_combo_validate in core/modules/date/date.elements.inc
Validate and update a combo element.
date_limit_format in core/includes/date.inc
Limits a date format to include only elements from a given granularity array.
date_parts_element in core/modules/date/date.elements.inc
Creates form elements for one or more date parts.
date_popup_element_value_callback in core/modules/date/date.elements.inc
Element value callback for date_popup element.
date_popup_input_date in core/modules/date/date.elements.inc
Helper function for extracting a date value out of user input.
theme_date_display_combination in core/modules/date/date.theme.inc
Returns HTML for a date element formatted as a Start/End combination.
_date_popup_process_time_part in core/modules/date/date.elements.inc
Process the time portion of the element.